Power transmission device



April 1935. H. e. JOHNSTONE EI'ALV 1,996,579

POWER TRANSMISSION DEVICE Filed June l5, 1932 l/VVE/VTORS I H 6. JOHNSTOA/E l D. BAR/rm ATTO/PIVE) Patented Apr. 2, 1935 UNITED sTA'rs POWER TRANSMISSION DEVICE Harold G. Johnstone, Chicago, Ill., and Virgil D. Barker, Westfield, N. J.

Application June 15, 1932, Serial No. 617,332

13 Claims.

This invention relates to power transmission devices, and more particularly to a mechanism for transmitting power from a plurality of prime movers on aircraft to a single propeller driving shaft.

In the operation of aircraft and particularly In practice this expectation has not been fully i realized and serious accidents have resulted from the failure, during flight, of one or more of a plurality of aircraft motors. This has been caused due to the fact that when a plurality of.

independent power plants are provided some of them must of necessity be displaced laterally from the center of drag of the airplane in order to secure the greatest efiiciencyfrom the driving propellers. Then, in the event of failure of a motor which is displaced from the center of drag, the driving thrust of the propellers is unbalanced causing a large yawing moment in the direction of the inoperative motor which yawing moment will be aggravated by the wind resistance of the inoperative propeller. This large yawing moment must be overcome'and necessitates the application of a great amount of rudder thereby further tending to slow down the aircraft and reducing the maneuverability of the aircraft.

The failure of one motor of multi-motored airplanes, as heretofore known, has thus made.

the airplanes slow down due to decreased power and increased drag thereby causing the propellers to operate at lowered efficiency and the ac tive motors, necessarily slowed down, deliver less than their maximum power.

It is an object of the present invention to provide a simple, compact and highly efficient transmission device.

Another object of the invention is the provision of a transmission device adapted normally to be driven by a plurality of motors for transmitting power to a single shaft.

Still another object is the provision of a transmission device for aircraft power units which may be driven by either or both of a pair of motors and which transmits the power with equal efficiency from either one or both motors to a single propeller.

In accordance with one embodiment, the invention contemplates a power transmission 'unit particularly adapted to aircraft which is capable of supplying propeller driving energy to 'a propeller shaft mounted on the vertical centerline of drag of the airplane,from two motors at a predetermined propeller speed and upon failure v of one motor the other motor will continue to drive the propeller shaft at aspeed less than when both motors were operating, thereby to provide the maximum propeller efiiciency when either one or both of the motors are operating. That is, the transmission is so arranged that either motor can drive the propeller in the event of failure of the other and, in addition, the speed ratio between the single motor and the propeller with only one motor operating can be deter-.

mined independently of the ratio between the propeller and both motors when both motors are running. With such an arrangement the airplane can be built with optimum propeller-and motor speed relations for each of the driving, conditions. Furthermore, the transmission serves the function of a reducing gear assembly between the motorsand the propeller to effect, I in a well known manner, a reduction of the'noise, of operation of the airplane and an increase in propeller efficiency.

An understanding of the invention will be had by reference to the followingdetailed description of one embodiment thereof, when considered in conjunction with the accompanying drawing, wherein I 1 P Fig. 1 is a plan view of a transmission unit, embodying the invention, with a portion of the casing removed, and p Fig. 2 is a fragmentary sectional view taken substantially along the line 2-2 of Fig. 1 in the direction of the arrows.

Referring now to the drawing wherein like reference characters designate the same parts throughout the several views, the numerals l and 2 designate support brackets which-- are secured to the housings or blocks of two motors (not shown) mounted in the fuselage of an aeroplane. The brackets support a gear box 3 in which are journaled the ends'of a pair of crank.

. shafts t and 5 driven by'the motors. The gear ment mountedin the gear box 3. Mounted upon and. keyed to the propeller shaft 6 is a ring gear I which meshes with pinion gears 8 and 9 mounted upon the shafts 4 and 5, respectively, and which has rotatably mounted therein a pair of beveled planet pinions l0 and H. The beveled planet pinions l0 and H are mounted in slots 12 and I3, respectively, cut in the ring gear and are supported on stud shafts hi and i5 journaled in bearings lB--!B and l'l--l'l positioned diametrically .opposite to each other on the ring, gear. iThe beveled planet pinions-l0 and ll mesh with a pair of large beveled gears l8 and i9 which are secured to a pair of gearsizil and 2|, respectively, freely rotatable on the propeller shaft 6 and meshing witli a pair of pinion gears 22 and 23 mounted uponi the shafts 4iand15. The gears 8, 9, 2 2 and 23 are'all of -theusame type, differing only in size, and are mounted upon their shafts in such a manner that when the shafts 4 and 5 are rotating in the directioniindicated by the arrows the gears will be driven sbyethe shafts (unless :the ;.gear is :rotating at a faster rate of speed than -.the-shaft, 'in which eevent thegearwilloverrun 'theshaft. The gears .8: andr-2 2 are exactlyvthessame as the gears v9 and 2.23, rrespectivel-y, and :the method of :mounting rfor only the gearsrl and [-23 --willbe described in at.250.0 revolutions'penminute 01"500 revolutions (detail.

rAdjacent .the lower wall-(Fig. .-l) of the gear tbox ziihthe shaftt5 ,has,pinned thereto a "collar -:24 \whichabnts ahearing platei'2 5 secured a to the E-faeeeQf'thegear 23 forholding in-place aphir-ralityrof roller bearings ;26-25;positioned in-- slots i2'l--2-l .cnt in thes ear 23. ,;The-S10tS21-2"i ,are ,tapered in the direction "of vthe rotation of the shaftc5,.-so-thatwhen; the-shaft is rotating in the direction :of the .-arrows, the shaft will tend :to wedge :the: roller-bearings 26-26 in the reduced portionsmf the slotsto drive thergear, whereas ifrthe geareis rotatingqfaster than 'the -shaft ithe sshaft twill; f Qrce nthSITOHY :bearings into the :enlarged portiona of 3171185510173.

sAssecondv-bearingplate r23 is ISBCLllBd sto the other FSide Of nthe gear (-23 rand engages :a spacer remember 29. {Ihebearing plate 28: cooperates with I ;,the bearing plate 2 5 to hold the roller ;bearings -=2 'in their slots 21 :and ithe sspacer member :2 0 spaces thegea-n 23;.frorn .the'gearsS TWh lChi is :also

provided --,with .roller bearings :26-28/. in slots :2 'I-QJZ'l andi bearin latess2 5. aIIdLTZSTaDd'WhiCh. is

held in place against the spacerrmember :29'by' 4 a-collar -30;pinned to:,the:shaft :-5.

The gears r8 and 22 are constructed :and arranged; in; exactly the -same manner-as the gears -.9-:and r23 -.bein g held in; place upon the shaft'fl by collars 3i and 32 so that when the shaft 14 is :rotated in the-direction indicated .by. the .arrows the ,gears will be vadriveniby the shaft unless :the gears are rotated by theirrcooperatirrg gears T ,and ZiL-at a:1'ate=of speed greater than .theispeed of the shaft 4, iXl'iWhiChwBVBIlt thegearsiB and 22 will overrun the shafti irbut will not ;drive" it.

A-better;understanding iof "the invention-may "tionhasbeen described and definite gear ratios 1 be had by reference to the followingbrief descrip ,tion of theroperation thereof.

Assume that-thezmotors (not shown) associated with the shafts '4 and 5 are ofatype'which .operate at a maximum-efficiency whenrotating the sshaftsat-the rate ofZOOO revolutionsper minute, :andassumethatthe propeller to'be used will'absorb the power output of :the two motors when the propeller rotates at :IGGO-revolutionsper minute with both motors running and that :it "will vabsorb the poweiuoutput of onemotor at'800 revolutions per minute. With this assumed state .of iactsithe gears 1, 8, ;9, ,20, 2i :22 and ;23:must

compare in size as follows: The gears 8 and 9 must be of the same size and must be two-fifths as large as ring gear I; the gears 22 and 23 must be the same size and must be one-half as large as gears 20 and 2| which must be of the same size. In other words, the gears must have the following ratio with respect to each other:

gear 8: gear 7=gear 9: gear l=l:2 gear 22: gear120= geari'23: gear-121:! :2

If both motors are rotating their shafts 4 and 5 at 2000 revolutions per minute, gears 22 and '23 will rotate at 2000 revolutions per minute to drive-gearsilll and 2! at 1000 revolutions per minutelandwhen gears :20 and 2i are driven at the :sametspeed the planet pinions l0 and M will not be rotated about their respective stud shafts I4 52/111115 butwillberotated about the axis of the shaft fi at the same speed as the gears 20 and 2!;

that is, at 1000 revolutions per minute. The

planet pinionselfl and H in rotating :about' the [axis of E theshaft 16 will carrythe :ring gear l with :them at-a speed of $1090 revolutions .perminuteto .drive the propeller -shaft6 at 1000 revolutions per minute and since the ring gear 7 meshes :with

:thegears-ii and 9 the'gears Band?! WiuJJG rotated gperiminutefaster than-their respective shafts 4 :and #5 and due to the construction of the gears 8 and-.9 they will overrun their shafts liand'5.

TIT'OHE .of the :motors stops, for example, the rmotorifordrivingthe-shafts, andthe.other mortor continues torotate its shaft?) at 2000 revolutions per :minute, the shaft i5 willdrive the .agears :9 and 23qat 2000 :revolutions per minute. The gear 9 being :meshedwiththe .ring gear I gwill :qdrive :the i ring gear at 800 revolutions per 'minute :to rotate :the shaft :6 at 800 revolutions ,per minutex-andithe gear *23 being meshed with the gear 2| will drive-the gear .12! :at 1000-revolutionsper minuteyabout the shaft-:6 which is ,beingdriven ;by:the:ring gear :1 at 5800 revolutions ,PEI minute.

The ringgear I in ;its :rotation lWil]. carry -the ,planet ipinions Iii/arid H withlit about the axis:

of =thesshaftefirataa rate of 800 revolutions per -minute-1and since the"gear;2l is rotating in the :same direction at MOO-revolutions per minute i or :200 .rrevolutions per minute :fasterithan the speed of,rotationpfstheplanet pinions H1 andilt;

iaboutltheeshaft 6, there-will be a differentialloss of.;200revolutionszper gminute between the speed :ofthe ring geargand ,tl1e.spe'ed at which .the planet .pinions "Land I! will drivethegear'ls.

Therefore,-the :beveled :gear l8 andthegeariZfi I will -.be-;driven rbyithe-planet pinions l0 and i l at 600 revolutions per minute to cause'thegear 'v2-2ztorrotatezat. 1-200 revolutions per minute since itvmeshes'withthegear-r120, andthe gear 11 will :-drive .theiipiniongearfi-at-a rate of 2000 revolutions per-minute about its shaft 4.

, ,Although awspecific embodiment of theinvenhave been given,-it is 'to be understood thatthe invention iscapable of many modifications. For

example,it will be:obvious that theratios given may be varied and the transmission modified extensively :to @suit any combination of aircraft, motors-and: propellers without departing'from the -scope ofzthezinvention and a device of the pres-' As an illustration, it may 1 be desirable with certain combinations of aircraft and motors, in the event of failure of one motor, to operate the remaining motor at a higher speed and power output than under normal conditions and this may be accomplished by suitable modifications of the various gear ratios given in describing the specific embodiment disclosed in the specification. The invention is therefore to be limited only by the scope of the appended claims.

What is claimed is:

1. In a power transmission device, the combination of a driven member, two driving members, means for transmitting power from both of said driving members to the driven member, and an independently operable means operative upon removal of power from one of said driving members for transmitting power from the other driving member to the driven member.

2. In a power transmission device, a driven member, a plurality of power supplying shafts, a pair of gears mounted upon each power supplying shaft, gears mounted upon the driven member and individual to one of each of said pair of gears mounted upon the power supplying shafts, a gear fixed to the driven member and operatively associated with the others of said pairs of gears mounted upon the power supplying shafts, and means interconnecting said pair of gears individual to the gears on the power supplying shafts to cause said last mentioned pair of gears to drive the driven member when both of the power supplying shafts are operating and to cause one.of said gears common to the gear fixed to the driven member to drive the driven member when one of said power supplying shafts is not operated.

3. A power transmission device comprising a driven member, a plurality of driving members, means interconnecting the driven member and the driving members including means for transmitting power from all of said driving members to the driven member at a predetermined ratio between each driving member and the driven member, and normally inoperative interconnecting means operative upon a decrease in speed of one of said driving members for transmitting power from the other driving members to the driven member at a reduced ratio.

4. A power transmission device comprising a driven member, a plurality of driving members, means interconnecting the driven member and the driving members including means for transmitting power from all the driving members to the driven member at a predetermined ratio between the driven member and each driving member, and separate interconnecting means operative upon a decrease in speed of one of the driving members for changing the ratios between the driven member and the other driving member.

5. A power transmission device comprising a driven shaft, a pair of driving shafts, means interconnecting the driving and driven shafts, and means for varying the speed ratios by a separate interconnection between the driving and driven shafts when the torque ratio between the driving shafts varies.

6. A power transmission device comprising a driven shaft, a pair of driving shafts, means interconnecting the driving and driven shafts, and means operative upon a variance in the speeds of the driving shaftsfor interconnecting the driving and driven shafts independently of the first named interconnecting means.

7. A power transmission device comprising a driven shaft, a pair of driving shafts, means interconnecting the driving shafts with the driven shaft, and a separate interconnecting means for varying the speed ratio between one driving shaft and the driven shaft upon a change of torque supplied to the other driving shaft.

8. In a power transmission device, a-driven shaft, two driving shafts, means for differentially transmitting power from both of the driving shafts to the driven shaft, and means operable upon a reduction of the speed of either driving shaft for transmitting power independently of said differential means from the other driving shaft to the driven shaft. I

9. In a power transmission device, a driven shaft, two driving shafts, gears for transmitting power from both of the driving'shafts to the driven shaft at a predetermined speed ratio, and normally inoperative gears operable upon a reduction of the speed of either driving shaft for transmitting power from the other driving shaft to the driven shaft at another predetermined speed ratio.

10. In a power transmission device, a driven shaft, a plurality of driving shafts, gears for differentially connecting all of the drivingshafts to the driven shaft, and a gear associated with each driving shaft for automatically connecting said shaft independently to the driven shaft upon a failure of power in others of the driving shafts.

11. In a. power transmission device, a driven shaft, two driving shafts, differential gearing for connecting both of the driving shafts to the driven shaft and additional gearing associated with each of said driving shafts, to automatically connect either one of the driving shafts tothe driven shaft upon the failure of power in the other driving shaft.

12. In a power transmission device, a driven shaft, two driving shafts, differential gearing for connecting both of the driving shafts to the driven shaft and non-differential gearing, normally inoperative, for automatically connecting either driving shaft to the driven shaft upon failure of power in the other driving shaft.

13. In a power transmission device, a driven shaft, two driving shafts, means for transmitting a common drive from both driving shafts to the driven shaft, and normally inoperative means associated with each of said driving shafts arranged to become operative automatically for transmitting an individual drive to the driven shaft from said associated driving shaft upon failure of power in the other driving shaft.

HAROLD G. JOHNSTONE. VIRGIL D. BARKER. 

